The present invention relates to a system for extending the useful life of compressor lubricants. More particularly, the present invention relates to an acid-filtered lubricant system for a compressor.
Most compressors are either contact cooled or oil-free. Contact cooled compressors are generally defined as compressors that inject a lubricant into the compression chamber to lubricate, remove the heat of compression, and seal the clearances between moving components such as compressor rotors, or the like. Oil-free compressors are generally defined as compressors that separate the air and oil systems, if required, to prevent contamination of the compressed air. In both cases, the air and lubricant must be cooled to remove the heat of compression and heat from friction.
In conventional air compressor systems which utilize a contact cooled compressor, air is compressed in a compression chamber or airend (by a set of rotary screws, for example). A lubricant, such as oil, is injected into the compression chamber and mixes with the compressed air. The lubricant is generally injected into the compression chamber for a number of reasons including cooling the air compressor system, lubricating bearings, balancing axial forces and sealing the moving parts. After compression, the lubricant must be removed from the stream of compressed air before the compressed air may be used downstream for pneumatic tools and/or other equipment or applications.
While many variations on the separation process have been explored, many compressor units today use a two step separation process. The heavily saturated air/lubricant mix discharged from the airend enters a separator tank and is mechanically separated by means of a centrifugal impingement process on the inside wall of the separator tank and through gravity. Alternatively, a system of baffles may be used to turn the flow one or more times in order to force the lubricant to separate by impingement on the baffles and/or wall of the separator. The separated lubricant (taken out of the air/lubricant mix) is deposited in the sump of the separator tank before being piped back through a main liquid cooler and finally re-injected back into the airend. The partially separated air that contains the remaining lubricant is then passed through a secondary separator filter where the air is “cleaned”. The cleaned air passes through a minimum pressure check valve or the like and travels downstream to desired downstream components. The lubricant removed from the air within the separator filter drains to the bottom of the separator filter whereupon it is collected and returned to the airend.